comparison toolboxes/FullBNT-1.0.7/bnt/CPDs/@tabular_CPD/bayes_update_params.m @ 0:e9a9cd732c1e tip

first hg version after svn

+function CPD = bayes_update_params(CPD, self_ev, pev)
+% UPDATE_PARAMS_COMPLETE Bayesian parameter updating given completely observed data (tabular)
+% CPD = update_params_complete(CPD, self_ev, pev)
+%
+% self_ev(m) is the evidence on this node in case m.
+% pev(i,m) is the evidence on the i'th parent in case m (if there are any parents).
+% These can be arrays or cell arrays.
+%
+% We update the Dirichlet pseudo counts and set the CPT to the mean of the posterior.
+
+if iscell(self_ev), usecell = 1; else usecell = 0; end
+
+ncases = length(self_ev);
+sz = CPD.sizes;
+nparents = length(sz)-1;
+assert(nparents == size(pev,1));
+
+if ncases == 0 | ~adjustable_CPD(CPD)
+  return;
+elseif ncases == 1 % speedup the sequential learning case by avoiding normalization of the whole array
+  if usecell
+    x = cat(1, pev{:})';
+    y = self_ev{1};
+  else
+    x = pev(:)';
+    y = self_ev;
+  end
+  switch nparents
+   case 0,
+    CPD.dirichlet(y) = CPD.dirichlet(y)+1;
+    CPD.CPT = CPD.dirichlet / sum(CPD.dirichlet);
+   case 1,
+    CPD.dirichlet(x(1), y) = CPD.dirichlet(x(1), y)+1;
+    CPD.CPT(x(1), :) = CPD.dirichlet(x(1), :) ./ sum(CPD.dirichlet(x(1), :));
+   case 2,
+    CPD.dirichlet(x(1), x(2), y) = CPD.dirichlet(x(1), x(2), y)+1;
+    CPD.CPT(x(1), x(2), :) = CPD.dirichlet(x(1), x(2), :) ./ sum(CPD.dirichlet(x(1), x(2), :));
+   case 3,
+    CPD.dirichlet(x(1), x(2), x(3), y) = CPD.dirichlet(x(1), x(2), x(3), y)+1;
+    CPD.CPT(x(1), x(2), x(3), :) = CPD.dirichlet(x(1), x(2), x(3), :) ./ sum(CPD.dirichlet(x(1), x(2), x(3), :));
+   otherwise,
+    ind = subv2ind(sz, [x y]);
+    CPD.dirichlet(ind) = CPD.dirichlet(ind) + 1;
+    CPD.CPT = mk_stochastic(CPD.dirichlet);
+  end
+else  
+  if usecell
+    data = [cell2num(pev); cell2num(self_ev)]; 
+  else
+    data = [pev; self_ev];
+  end
+  counts = compute_counts(data, sz);
+  CPD.dirichlet = CPD.dirichlet + counts;
+  CPD.CPT = mk_stochastic(CPD.dirichlet);
+end